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Benzylideneacetone

Benzylideneacetone

IUPAC name	4-Phenyl-3-buten-2-one
Other names	Benzalacetone Benzylideneacetone Methyl styryl ketone Benzylidene acetone
Identifiers
CAS number	122-57-6
RTECS number	EN0330000
Properties
Molecular formula	C₁₀H₁₀O
Molar mass	146.19 g/mol
Appearance	pale yellow solid
Density	1.008 g/cm³
Melting point	39-42 °C
Boiling point	260-262 °C
Solubility in water	1.3 g/L
Solubility in other solvents	nonpolar solvents
Hazards
Main hazards	irritant
R-phrases	36/37/38-43
S-phrases	22-26-36/37
Flash point	116 °C
Related Compounds
Related compounds	Dibenzylideneacetone cinnamaldehyde
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Benzylideneacetone is the organic compound described by the formula C₆H₅CH=CHC(O)CH₃. Although both cis and trans isomers are possible for the α,β-unsaturated ketone, only the trans isomer is observed. Its original preparation demonstrated the scope of condensation reactions to construct new, complex organic compounds.^[1]

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Preparation

Benzylideneacetone can be efficiently prepared by the NaOH-induced condensation of the readily available reagents acetone and benzaldehyde:^[2]

CH₃C(O)CH₃ + C₆H₅CHO → C₆H₅CH=CHC(O)CH₃ + H₂O

Reactions

The compound undergoes the reactions expected for its collection of functional groups: e.g., the double bond adds bromine, the heterodiene adds electron-rich alkenes in Diels-Alder reactions to give dihydropyrans, the methyl group undergoes further condensation with benzaldehyde to give dibenzylideneacetone, and the carbonyl forms hydrazones. Treatment of benzylideneacetone with the Grignard reagent methyl magnesium bromide followed by acid-induced dehydration gives 1-phenyl-1,3-butadiene.^[3] It reacts with Fe₂(CO)₉ to give (benzylideneacetone)Fe(CO)₃, a reagent for transferring the Fe(CO)₃ unit to other organic molecules.^[4]

References

^ Claisen, L. “Über die Einwirkung von Aceton auf Furfural und auf Benzaldehyd bei Gegenwart von Alkalilauge” Berichte der deutschen chemischen Gesellschaft 1881, volume 14, p 2468-2471.
^ Drake, N. L.; Allen, Jr. P.. "Benzalacetone". Org. Synth.; Coll. Vol. 1: 77.
^ Grummitt, O.; Becker, E. I. (1963). "trans-1-Phenyl-1,3-butadiene". Org. Synth.; Coll. Vol. 4: 771.
^ Knölker, H.-J. "(η⁴-Benzylideneacetone)tricarbonyliron" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.